1. Field of the Invention
The present invention generally relates to a set-top box having an improved patch antenna. More particularly, the invention relates to a set-top box having an antenna provided on a front panel circuit board.
2. Background of the Invention
As consumers acquire more electronic devices they continually look for ways to integrate them into a single multifunctional system providing them with an efficient single point of control. Generally a single device lies at the nexus of an integrated system allowing each of the components to interface. One such device for allowing this kind of interfacing is known as a “set top box.” Typically, a set top box connects to a television set and interfaces various media such as cable television broadcasts, satellite signals, stereo components, internet connections via a telephone line, DVD and VCR devices, and other types of electronics and communication media.
Although a system, such as a set top box, in which multiple devices are interconnected furnishes a method of control, such devices have certain disadvantages. For instance, such systems traditionally require a large number of electrical cables to interface to the set top box. Cables can be expensive and are generally cumbersome, unattractive, and often limited to small areas unless one is willing to run cables throughout the home or office. In addition, the set top box must be designed to receive the vast array of connectors that may be found on the various media. One way of overcoming these disadvantages is to have a wireless system.
One wireless protocol gaining popularity is “Bluetooth” technology which has been developed as an open standard for wireless communication of both data and voice. It is based on a relatively low-cost, short-range radio frequency (“RF”) link facilitating protected ad hoc connections for stationary and mobile communication environments. Bluetooth provides a universal bridge to existing data networks, a peripheral interface, and a mechanism to form small private ad hoc groupings of connected devices away from fixed network infrastructures. It enables users to connect a wide range of computing and telecommunication devices easily and simply, without the need to buy, carry or connect cables. Bluetooth also offers a more reliable wireless link than traditional protocols due to its fast acknowledgement and frequency hopping scheme. Because Bluetooth typically hops faster and uses shorter packets of data than other systems, it works with much less interference from other signals in “noisy” environments.
Some of the characteristics of the Bluetooth technology include: operation in the unlicensed Industrial-Scientific-Medical (“ISM”) band of 2.4 GHz; a Frequency Hop (“FH”) transceiver which divides the band into a number of hop channels and allows a connection to hop from one channel to another in a pseudo-random fashion during use; support for up to eight devices in a piconet (two or more Bluetooth units sharing a channel); built in security; non line-of-sight transmission through walls and certain types of cases; it is traditionally omni-directional; and supports both isochronous and asynchronous services; such as easy integration of TCP/IP for networking. Bluetooth was developed primarily to support computer networks.
Wireless communication systems generally require antennas to receive and transmit the information. A variety of antenna designs exist and it is not a trivial task to design a suitable antenna for a given application. There are a number of problems that must be addressed when choosing an appropriate antenna type and designing the particular antenna configuration. Such design considerations include the desired frequency range, size and shape of the pattern of coverage of the antenna, and other issues. The performance of many types of antennas is effected by metal surfaces located in close proximity to the antenna. Such metal surfaces can, to a certain extent, short circuit the antenna rendering it useless or at least significantly decreasing its performance. Antennas generally should not be placed inside a metal enclosure because the enclosure will shield the antenna thereby precluding the antenna to transmit a signal to the outside of the enclosure and precluding exterior-generated signals from penetrating the enclosure to be received by the antenna. Further, if placed outside the metal enclosure, it is still important for the enclosure not to interfere with the antenna's transmission and reception capability.
The present invention addresses the problem of designing an antenna system for a device with a metal enclosure (e.g., a set top box). Such an antenna design must address several problems. First, the location of the antenna should not be inside the metal enclosure because of the problem noted above. Second, if the antenna is placed on the outside of, but close to, the metal enclosure, the metal enclosure may still detrimentally interfere with the antenna's performance. Third, it is usually preferably for the owner of the device not to have to concern himself or herself with the placement and orientation of an antenna. Accordingly, a solution to these problems is needed.
One such solution is described in related U.S. patent application Ser. No. 09/685,506, which was incorporated by reference above. The patch antenna described therein, however, is unsuitable for use on a thin FR-4 circuit board. Ongoing efforts to reduce device size make it desirable to use this thinner circuit board material. Accordingly, a new patch antenna design is needed.